Avoid wearing vintage in poor condition. Just because a piece is vintage, doesn’t mean that it’s in good condition (or style) to wear. If your vintage piece has any visible damage including stains, tears, or missing parts, it should be avoided until brought to a tailor or seamstress. Have all your vintage pieces dry-cleaned prior to wearing, as they often come with smells and wrinkles that are hard to get out on your own at home.
The same applies for wearing vintage pieces that are clearly not your size.